Re: [Discuss-gnuradio] Synchronize USRP using 5Hz pps

[Sangho Oh]

It passes the pps test.

I just thought it is not working properly because the clock is too fast (5x than pps), and reading time is less than 1 sec.

If that is normal, then my GPS pps signal may be working correctly

- Sangho

---------------------------------------------------------------------

Creating the usrp device with: ...

Current recv sock buff size: 50000000 bytes

Using Device: Single USRP:

  Device: USRP2/N Series device

  Mboard: USRP2-REV3 mboard

  RX DSP: USRP2-REV3 ddc0

  RX Channel: 0

    RX Dboard: USRP2-REV3 dboard (rx unit)

    RX Subdev: XCVR2450 (0x0061)

  TX DSP: USRP2-REV3 duc0

  TX Channel: 0

    TX Dboard: USRP2-REV3 dboard (tx unit)

    TX Subdev: XCVR2450 (0x0060)

Set time to known value (100.0) without regard to pps:

Reading time 1 second later: 101.000101

Set time to known value (0.0) at next pps:

Reading time 1 second later: 0.871597

Success!

On Tue, Jan 18, 2011 at 8:45 PM, Josh Blum <address@hidden> wrote:

Using a 5Hz PPS is not fundamentally different than 1Hz. That should not
be a problem.

Make sure your pulse has the correct levels:
http://www.ettus.com/uhd_docs/manual/html/usrp2.html#pps-pulse-per-second

-Josh

On 01/18/2011 05:36 PM, Sangho Oh wrote:
> Hello,
>
> I am using Garmin 18 5Hz PPS clock for USRP synchronization.
>
> This is the GPS: https://buy.garmin.com/shop/shop.do?pID=8631
>
> However, because it is 5Hz PPS not 1Hz, the synchronization looks not
> working properly.
>
> I got following message on the time stamp reading after 1 sec.
>
> "Creating the usrp device with: ...
> Current recv sock buff size: 50000000 bytes
> Synched to PPS: Reading time 1s later: 0.829645"
>
> As you see, the time reading after 1 sec is smaller than 1 sec.
>
> I am wondering if I have to buy another GPS for 1 Hz PPS.
>
> Thanks.
>
> - Sangho
>
>
>
>

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From: Sangho Oh

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